Consider an acute-angled

MATHEMATICS · Subjective · IB Diploma Programme · Mathematics: Analysis and Approaches · Geometry and Trigonometry · Geometry and Trigonometry

Problem

\Delta ABC

. Let

AD

BE

, and

CF

be the altitudes drawn from the vertices to the opposite sides. Prove that

\frac{EF}{a}+\frac{FD}{b}+\frac{DE}{c}=\frac{R+r}{R}